Investigation on Effectiveness of Wheat Stem Rust Resistance Genes in Iran and the Latest Response of Wheat Genotypes from the Cold Agro-climatic Zone to the Disease

Wheat stem rust, caused by Puccinia graminis f. sp. tritici, is the most destructive rust of wheat. In this study, in addition to determining the effectiveness of rust resistance genes, the responses of 48 wheat genotypes from the cold agro-climate zone of Iran, including commercial cultivars, candidate lines, and the lines of ERWYT-C-94 were determined to the disease. Disease score of differential cultivars carrying resistance genes to stem rust under field conditions showed the presence of virulence on 31 resistance genes. In this regard, virulence on Sr31 was new for Kelardasht and on Sr1RSAmigo and SrSatu for the whole country. Seedling evaluations of wheat genotypes in the greenhouse showed that three commercial cultivars including MV-17, Pishgam, and Gascogne, four candidate lines including C-88-7, C-88-14, C-89-7, and CD-89-10, and the elite line C-94-6 displayed the lowest infection types to different isolates of P. graminis f.sp. tritici. Adult-plant evaluations under field conditions showed that the candidate line CD-89-10, showing the response of 20R, was the most resistant line among all genotypes tested. Two candidate lines CD-90-4 and CD-90-8, displaying low infection types to most of the isolates, were also among the genotypes with good level of resistance to the disease at seedling stage. These lines, with the responses of 20MR and 40MR, respectively, had also acceptable levels of resistance at adult-plant stage. Considering high frequency of susceptible genotypes to stem rust in cold zone, especially the promising lines, transferring effective stem rust resistance genes to wheat cultivars for this zone is necessary.